Fuel burner



March 19, 1946. J. A. MASON FUEL BURNER Filed'ipril 5, 1944 2Sheets-Sheet 1 Emu S w & mi am a, Q QM \MY 0 \lm & m mi NN Q mm mm m a Va mm 9 a m nm E m Q m 3 A TTORNE Y Mmh 19, 1946. J. A. MASON FUEL BURNERFiled April 5, 1944 2 Sheets-Sheet 2- Fig. 3

' IINVENTOR Jacob A. Mason .1 ATTORNEY Patented Mar. 19, 1946 FUELBURNER Jacob A. Mason, Newark, N. J., assignor to The Babcock & WilcoxCompany, Rockleigh, N. J a corporation of New Jersey Application April5, 1944, Serial No. 529,553

4 Claims.

The present invention relates in general to the construction andoperation of fluid fuel burners, and particularl to an improvement inthe construction and the operation of fluid fuel burners utilizing aconical spray of atomized fuel discharging through a burner port into aswirling stream of air.

The main object of this invention is to provide a device in'a fluid fuelburner of thegeneral type described, for directing the flow of airthrough the body of the burner in a manner improving the mixing actionof the entering fuel and air, and thus facilitating rapid and completecombustion of the fluid fuel. A further and. more specific object is theprovision of a fluid fuel burner construction which in operation avoidscombustion conditions tending to cause pulsations in the associatedfurnace. The invention is of particular importance and utility in highcapacity furnaces with restricted volumetric dimensions, whereincombustion conditions must be maintained which minimize pulsations, dueto the adverse effect of such pulsations on the furnace efficiency. Forexample, fuel burners incorporating the invention have been successfullyused over a wide operating range in high capacity marine water tubeboilers having an effective furnace depth of only 6 feet, withoutfurnace pulsations and with a high combustion eficiency.

A better understanding of the present invention will be obtained breference to the drawings and descriptive matter illustrating apreferred embodiment of my invention and attached hereto. The novelfeatures of this invention are pointed out with particularity in theclaims forming a part of this specification.

Of the drawings:

Fig, 1 is an elevation, partly in section of a mechanical atomizingliquid fuel burner incorporating my invention;

Fig. 2 is a view of the shroud member taken on line 22 of Fig. 1;

Fig. 3 is a perspective view of the burner port ring;

Fig, 4 is an enlarged view partly in section of the louver adjustingcrank and gear assembly; and

Fig. 5 is a view of an individual air louver blade illustrating thechange in radius of the louver tip on rotation about its axis and itsrelation to the shroud member.

In the drawings the invention is illustrated as incorported in a liquidfuel burner of the type shown in U. S. patent 2,260,062. As shown, theburner is mounted in a vertical wall ill of a suitable furnace II andarranged coaxially of a circular burner port 12 in the furnace wall. Theport i2 is defined by suitable refractory material tapering to asubstantially circular throat at an intermediate point. A metallic portring l3, shaped as a truncated cone defines the outer section of theburner port and has a flanged outer end rigidly secured to the metalcasing I of the furnace wall iii. As shown in Fig. 3, the port ring I3is formed with its. inner discharge edge section shaped to form aregular decagonal surface at the inner side of the port throat section.A symmetrical series of air directional vanes i5 are located oncorresponding flat surfaces of the port ring l3, each vane projectinginwardly toward the axis of the burner port and arranged with itsfurnace or inner edge meeting the fur.- nace edge of the ring 13 at thecenter of each flat of the decagonal inner surface, and the base of eachvane pitched at an angle of approximately 30 to the plane of the furnaceedge of the ring. The furnace edge of each vane i5 slopes outwardly awayfrom the furnace at an angle of approximately 45 to the plane of thefurnace edge of the ring, a bend being formed in the vanes near thefurnace edge whereby the pitch angle is increased an additional amount,approximately 15. The vanes have rounded inner ends, which merge with asubstantially straight outer edge arranged approximately perpendicularto the internal surface of the port ring.

The burner port ring i3 and vanes l5 impart a counterclockwise swirl tothe stream of air passtween the walls forming a passageway llsurrounding the body of the burner for the flow of preheated combustionair to the burner port.-

Preferably these walls are spaced approximately 16 inches apart. Airflow from the space ll toward the furnace I I is caused by maintainingthe air pressure in the space greater than the operating pressure in thefurnace.

A circular cover plate It closes an access opening in the wall i6arranged coaxially of and of larger diameter than the burner port ring.The plate i8 is provided with a heat protective covering of insulatingmaterial 42held in place by metallic sheet 43 and is rigidly'connectedby struts 23 to the outer circumference of an air register ring 24carried by a spool section 25 which in turn is fixed to the burner portring,

the parts 28 and 24 forming acontinuation of,

the ring l3. Cover plate I 8 supports a central hub member is throughwhich extends a burner barrel 20 having a fuel supply assembly 2| on itsouter end and an atomizer head 22 on its inner or furnace end. Theatomizing head 22 is'prefsurface having a'series of equally spacedopenin s and corresponding deflector plates therein.

A circular series of segmental louver blades 21 are pivotally mountedwithin the annular space between ring 24 and barrel 20 by pins 28 and29. The rotational axis of each louver blade, as shown in Figs. 1 and 5is at an oblique angle of approximately 60 to the axis of the barrel 20.Furthermore, the blades 21 are adjustable about blades has beendemonstrated in practice. The

main advantage lies in causing the combustion air passing through thecircular opening of the annular end plate to engage the leading edge ofthe louver blades and to be directed in limited rotational movement inproportion to the transverse angularity of the blades, the effect of theblades on the air flow being to minimize the formation of localized eddycurrents of air detrimental to an equalized flow of the combustion airthrough the burner throat.

It will be observed, by reference to Fig. 5, the anguiarity of thelouver blade axis with respect to the axis of the burner barrel causes achange inthe radius of the blade tip 40, as projected into the plane ofthe annular end plate 39, on rotation of the blade on its axis. When theblades are in their wide open position, the projected diameter of thetips in the described plane will be at the maximum value and at the'minimum value when the blades are rotated into the closed position. I havefound by operating tests that the diameter of the annular end ringopen-' ing 4| should be equal to or less, but should not their axes bymeans of pinions engaging a ring gear 3| on a rotatable sleeve 32. Thesleeve 32 is operated by the mechanism shown in Fig. 4, consisting ofgears 33 and 34, shaft 35, and crank 36. The crank 36 is angularlymovable to predetermined positions to rotate the louver blades 21 andthereby control the quantity and direction of the combustion airdelivered to the fluid fuel burner. In Fig. l the louver blades areshown inia wide open position permitting maximum flow of combustion airtherethrough. When in this position the leading edge 31 of theblades-will be substantially perpendicular to the axis of the burner.

In accordance with the present invention, a cylindrical shroud member 38is formed concentrically with and circumferentially enclosing the seriesof louver blades 21, the inner edge of the shroud 38 registering withand welded to the outer edge of the air register ring 24 and thusdefining a cylindrical outer end portion for the passageway directingthe flow of combustion air from the space I! into the burner port,wherein it intersects and mixes with the conical spray of fueldischarging from the atomizer head 22. The outer end of the shroudmember 38 .has an annular end plate or flange 39 welded thereto in aplane transverse to the axis of the burner barrel.

The axial length of the shroud member 38 is made suflicient to permitthe full opening of the louver blades without having the blades contactwith the annular end plate. 39. .The circular opening 4| in the endplate 39 is coaxial with the burner barrel, the diameter of the openin4| being preferably less than the internal diameter of the ring 24 atthe pivot pins 28 of the louver blades 21, and greater than the diameterof the burner port throat.

More specifically, as shown in Fig. 5, the radius of the annular endplate opening 4| is slightly less than the radius of a projection, in aplane normal to the plane of the annular end plate. of the louver bladeleading edge tip 40 when the blade is in its closed position.

The importance of the described relation of the diameter of the annularend plate opening to the location of the leading edge tip of the louverbe greater than the minimum blade tip diameter as projected in the plane'of the annular ring opening to secure the optimum results.

In the drawings the axial length of the shroud ring is approximately 4/2" and the outer diameter of the concentric end plate opening 4| is ofthe order of 20 inches. The enclosure formed by the concentric sectionscomprising the spool member 25, air register ring 24 and shroud member38 extends outwardly from the furnace wall and within space I!approximately ten inches,

leaving a substantially unobstructed air space between the outer end ofthe shroud member 38 and the cover plate l8 of approximately six inches.The space between the impeller plate 26 and the shroud end plate 39provides ample room to position the louvers without interfering with theproper functioning of the related parts of the fluid fuel burner.

Inoperation combustion air flows through the air passage l1 towards theend plate opening 4|, passing through the opening and into the louversin generally axial flow relative to the axis of the burner. Since theposition of the louver blades is dependent onthe quantity of airrequired for proper combustion of the fuel delivered to the furnace, theblades may be either wide open or at some partially open position. Atany partially open position the blades will be at an angle transverse tothe direction of air flow and will cause a clockwise swirl of theentering air, the intensity of swirl depending on the degree ofangularity of the blades. The combined effect of the shroud member andthe louver blade facilitates equalization of the flow of air throughoutthe area of the space surrounding the fuel burner barrel, greatlyimproving the combustion efficiency of this type burner.

In one installation where the fuel burning apparatus described wasapplied to a small furnace having an eiiective depth only four timesgreater than that of the burner throat diameter, the elimination offurnace pulsations and the increase in combustion efliciency wasparticularly outstanding in comparison with imilar burners without thedescribed shroud member.

I claim r 1. In combination with a furnace wall having a fuel burnerport therein, a casing spaced from said wall to form an air spacetherebetween, a fluid fuel burner nozzle arranged coaxially of andaseaser discharging a stream of fluid fuel through said burner port, andmeans for directing combustion air from said space into said burner portcomprising a ring member forming a. continuation of said burner port, acircular series of air directing blades surrounding said burner nozzlewithin said ring member, and a shroud member forming a continuation ofsaid ring member in said air space and having a central air inlet at theouter side.

of said air directing blades with a diameter not greater than the airdirecting blade tip diameter. 2. A. liquid fuel burner comprising abarrel with v an atomizing head in one end thereof, a burner port ringarranged coaxial with said barrel, a ring member forming an outwardcontinuation of said port ring, a series of segmental louver bladespivotally supported between said ring member and said barrel with thepivotal axes thereof obliquely intersecting the axis of said barrel, anannular shroud ring forming an outward extension of said ring member andenclosing the periphery of said louver blades, and an annular end platehaving a central opening of a diameter les than the diameter of theadjacent edges of said louver blades projected into the plane of saidplate opening.

3. In combination with a furnace wall having a fuel burner port therein,a casing spaced from said wall to form an air space therebetween, afluid fuel burner nozzle arranged co-axialiy of and discharging a streamof fluid fuel through lit saidburner port, and means for directingcombustion air from said air space into said burner port comprising aring member forming a continuation of said burner port, a circularseries of pivotally mounted segmental airlouver blades surrounding saidburner nozzle within said ring member, and a shroud member forming acontinuation of said ring member in said air space and having a centralair inlet at the outer side of said louver blades with a diameter lessthan that of said louver blade series and greater than the minimumdiameter of said burner port.

4. In combination with a furnace wall having a fuel burner port therein,a fiuid fuel burner nozzle arranged coaxially of and discharging astream of fiuid fuel through said burner port, and means for directingcombustion air into said burner port comprising an air register ringforming a continuation of said burner port, a circular series ofpivotally mounted segmental air louver blade surrounding said burnernozzle within said register ring, and a shroud member forming acontinuation of said register ring and having a central air inlet at theouter side of 'said air louver blades with a diameter not greater thanthe minimum diameter of the leading edge of the tips of said louverblades as projected in the plane of said central air inlet.

JACOB A. MASON.

